microsoft powerpoint - oeo106040 lte eran6.0 scheduling feature issue 1

LTE eRAN2.1 Scheduling Feature

Confidential Information of Huawei. No

Spreading Without Permission 1

www.huawei.com

Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.



Contents

1. Overview

2. Downlink Scheduling

3. Uplink Scheduling

4. Semi-Persistence Scheduling

Page1





Scheduling Overview

Scheduling Function: Ensure high spectrum high spectral efficiency while providing the required.

Page2


Scheduling Strategy

SchedulingStrategy

Effect Factor Scheduling PriorityApplication Scenario

Max C/I Channel qualityThe UE with better channel quality has a higher priority in scheduling.

To verify the maximum system throughput

RR NoneEach UE has equal opportunity to be scheduled.

To verify the upper limit of scheduling fairness

PFService rate and channel quality

The UE with a small ratio between the service rate and channel quality has a higher priority in scheduling.

To verify the system throughput and fairness

EPF

Service rate, channel quality, UE capability, and QoS requirement

Intergraded priority with service rate, UE category, QoS and CQI.

In operating networks

Page3





Scheduling Scheme

• Period: 1ms (per TTI)

• Service application: all service

Dynamic scheduling

• Period: 20ms (Huawei eNodeB)

• Service application: Real time service, etc. VoIP

Semi-Persistent Scheduling

Page4


QoS Class Index

QCI Type PriorityPacket Delay

Budget

Packet Error

RateService Example

1 GBR 2 100ms 10-2 Conversational Voice

2 GBR 4 150ms 10-3 Conversational Voice

3 GBR 3 50ms 10-3 Real time gaming

4 GBR 5 300ms 10-6 Real time video

5 Non GBR 1 100ms 10-6 IMS signaling

6 Non GBR 6 300ms 10-6 Video with buffer

7 Non GBR 7 100ms 10-3 Voice, Video, Interactive Gaming

8 Non GBR 8 300ms 10-6 Video, TCP (HTTP, E-mail, FTP etc)

9 Non GBR 9 300ms 10-6 Video, TCP (HTTP, E-mail, FTP etc)

Page5





Scheduler Introduction

Scheduling in each TTI

Semi-persistent scheduling

Dynamic scheduling

Priority

calculation

MCS

selection

Resource

allocation

QoS management

Processing of measurement

quantities from PHY

Scheduling information

processing

UE capability

QoS (QCI/GBR/AMBR)

SINR (uplink)

CQI (downlink)

SR/BSR (uplink)

Buffer status(downlink)

PHR (uplink)

Tx power (downlink)

ACK/NACK

Virtual MIMO switch (uplink)

MIMO scheme (downlink)

ICIC strategyEdge frequency band

Center frequency band

RLC payload

MCS

Antenna and

resource mapping

Retransmission

control

Scheduler

The dashed line indicates the optional function.

Guarantee system

signaling sending

Ensure QoSrequirements

Take user differentiation and fairness into account

Maximize the system

throughput

Functions of MAC layer:

Page6


Scheduling Execution

� DCI info for scheduling

� Resource allocation header: indicate allocation type

� Resource assignment block

� MCS (Modulation Coding Scheme)

� MIMO scheme

� NDI( New Data Indication)

� HARQ process number

DCI info (PDCCH)

Page7





Contents

1. Overview




Page8


Contents


2.1 Scheduling Priority Processing

2.2 MCS Selection & Resource Allocation

Page9





DL Scheduler

DL Scheduler

Channel Quality

HARQ feedback

QoS parameters

UE Capability

Selected UE

RB number

MCS/MIMO

Every scheduling period

Priority calculation

MCS selection

Resource allocation

Page10


Scheduling Priority of DL Scheduling

Obtain scheduling resource

Control message scheduling

Semi-persistent scheduling

Retransmission scheduling

Initial transmission in dynamic scheduling

End

Re

so

urc

e a

lloca

tion

Page11





Control-Plane Data and IMS Signaling

� Common Control Messages

� Common control message regards to SIBs, paging and RA response

message.

� If the scheduling indication fails to be delivered due to insufficient

PDCCH resources , common control messages are not scheduled in the

current TTI.

� UE-Level Control Message or IMS Signaling

� SRB0 is delivered in the Contention Resolution message during the

random access process, has higher priority then SRB1/SRB2 and IMS

signaling

� During the DRX dormant period and measurement gap or when the UE

has urgent HARQ scheduling, SRB1 and SRB2 cannot be scheduled.

� The scheduling of IMS signaling is the same as that of SRB1 and SRB2

Page12


HARQ Retransmission Scheduling

At least 8 TTI

Page13





HARQ Retransmission Scheduling Exception� HARQ retransmissions cannot be performed for a UE in one of the

following states:

� The UE is in a measurement gap or enters a measurement gap

� The UE enters sleep time in DRX and the HARQ operating status

is discontinuous transmission

� The UE is non-synchronized to the eNodeB or a radio link failure

(RLF) occurs

� System information and IP Multimedia Subsystem (IMS) signaling

are already scheduled for the UE in the current TTI

� Semi-persistent scheduling is performed for the UE in the current

TTI.

Page14


Other Initial Service Scheduling

Priority 2

Priority 1

Page15





Other Initial Service Scheduling

Priority 2

Priority 1

Page16


Priority of GBR Service Scheduling

� The priority of GBR service is determined by the following

formula:

� f(CQI): indicates the channel quality.

� f(delay): indicate packet delay budget which is specified in

3GPP

.

)()(Pr delayfCQIfiorityGBR ×=

Page17





Priority of Non-GBR Service Scheduling� The priority of Non-GBR service is determined by the following

formula:

� eff: indicates the channel quality

� r: indicate historical service rate for the UE

� : indicates scheduling priorities corresponding to different

QCIs

� : indicates the service type weight. The service types are

bit torrent (BT) services and non-BT services

serviceQCIGBRnonr

effiority γγ ⋅⋅=

−Pr

QCIγ

serviceγ

Page18


Contents


2.1 Scheduling Priority Processing

2.2 MCS Selection & Resource Allocation

Page19





MCS Selection

� The eNodeB obtains the ITBS according to the adjusted

CQI.( eNodeB internal mapping )

� If frequency diversity scheduling is used, UE will adopt full band

CQI report

� If frequency selective scheduling is used, UE will adopt sub_band

CQI report

� If CQI adjustment is enabled, the eNodeB adjusts the CQI

reported by the UE and selects an MCS based on the adjusted

CQI, otherwise eNodeB use the original UE CQI report

� The eNodeB selects IMCS according to the mapping from ITBS to

IMCS. ( Specified in 3GPP)

Page20


CQI Report Procedure

� Step 1: eNodeB configure CQI report mode with

periodic or aperiodic mode

� Step 2: If it aperiodic report, eNB send UE list to

UL scheduler for CQI report scheduling

� Step 3: The UL scheduler sends the UL grant to

UE in the aperiodic CQI user list

� Step 4: UE send CQI report to eNodeB

� If periodic CQI mode configuration, UE reports the

CQI on PUCCH as RRC configuration

� If aperiodic CQI mode configuration, UE reports the

CQI on PUSCH as UL grant.

UL UL

SchedulerScheduler

DL DL

schedulerscheduler

CQI Mode CQI Mode

ConfigurationConfiguration

UEUE

2

13

AA--CQICQI PP--CQICQI

1

4

eNB

Page21





CQI Adjustment

� Why CQI adjustment

� The CQI report period is far greater than the scheduling period,

which leads to deviation between the CQI at the reported time

and CQI in scheduling.

� The reported CQI value depends on the UE measurement, and

it may not be very accurate sometimes.

� In order to maximize the system capacity, IBLER target other

than 10% may be more appropriate, then CQI adjustment is

required.

Page22


CQI Adjustment Switch

Page23





RB Calculation & Allocation

� RB calculation:

� The scheduler obtains the amount of data to be scheduled and the ITBS

and estimates the number of RBs to be scheduled based on the 3GPP

specification

� Based on estimate RB number and remaining power, eNodeB finally

decide the RB number

� RB allocation:

� If frequency diversity scheduling is used, eNodeB allocate all the RB from

lower end to the higher end of a frequency band based on full band CQI

report

� If frequency selective scheduling is used, eNodeB schedules the UEs to

frequency bands with the optimum channel quality. This brings frequency

selective gains.

Page24


Frequency Selective Scheduling Scheme

� Required aperiod sub_band aperiod CQI report

� Calculate user’s priority in each sub-band with user queue

� Allocate the resource in each sub-band based on user

queue

1 RBG

UE1 10 9 8 13 6 5…612

12 8 6 6 5 8

…

1011

13 10 11 10 7 5…910

…

…

UE2

UEn

Sub-band1

Sub-band2

Sub-band n

Page25





FSS VS FDS

FSS FDS

Page26


Contents

1. Overview




Page27





UL Scheduling Overview

� Scheduling on the uplink is more difficult than on the downlink

� Limited visibility of quantity of queued data per radio bearer

� Scheduler is unable to offer per-radio bearer grants

UL data

UL grant

(On PUCCH)

Scheduling Request

BSR & PHRPeriodic or

Event triggered

UE eNodeB

Scheduling among UEs

Logical Channel Prioritization &

Multiplexing

Page28


UL Scheduler

UL Scheduler

SINR

HARQ feedback

QoS parameters

UE Capability

Selected UE

Bandwidthallocation

MCS/MIMO

Every scheduling period

Priority calculation

MCS selection

Resource allocation

PHR/BSR/SR

Page29





UL Scheduling Procedure

� A basic function of UL

scheduling is to obtain PUSCH

resources. As the PUSCH,

PUCCH, and PRACH share the

UL bandwidth, the PUSCH

occupies the available UL

resources in addition to PUCCH

and PRACH resources.

Page30


TTI Bundling Scheduling

� Benefit

� It increases the UL cell edge user throughput and improve UL

coverage.

� There is more than 3db gain for uplink coverage

Page31





TTI Bundling Functionality

� A TTI bundle permanently consists of four TTIs. The same

data is transmitted during the four TTIs

Page32


Synchronized UL Retransmission

Page33





UL Dynamic Scheduling for Initial Transmissions

� UL dynamic scheduling for initial transmission perform three

operations:

� Selects UEs for UL scheduling

� Determines MCSs to be used

� Determines the number and positions of RBs to be allocated

Page34


UL MCS Selection

� The process of determining MCSs for UL scheduling consists of

three parts: SINR adjustment, initial MCS selection, and MCS

adjustment

SINR adjustment

IBLER

measurement

DRS

measurement

IBLER target

Adjusted

SINR

Initial MCS selection

Whether message 3

is transmitted on UL

MCS adjustment

SRS

transmission

UCI

transmission

UE

capability

Final MCS

Page35





SINR Adjustment

� Why SINR adjustment

� Due to fading effect, SINR measurement can not reflect the

actual channel quality

� SIRN adjustment is used to make the actual IBLER is

converged to the target IBLER

Page36


Initial MCS Selection & Adjustment

� On uplink, initial MCS selection is an internal decision by eNodeB

according to adjusted SINR

� MCS should be adjusted due to the following scenarios :

� To ensure the initial access performance, Huawei eNodeB uses a

fixed low-order MCS to transmit message 3

� If uplink data is conflict with UCI and SRS transmission, it will

cause higher IBLER, so the MCS should be adjusted

� If UCI(CQI/PMI/RI) is transmitted on PUSCH, it will use lower

MCS to ensure the performance based on a offset. In most of

scenario, the default offset can be used, and when the radio

environment is extreme bad, we can also adjust it manually.

Page37





Determine Number of RB

� The following info are required to determine number of RB

� Buffer report from UE

� Power headroom report from UE

� QoS satisfaction rate

� Maximum number of RBs supported by a single carrier

Page38


UL QoS Management

� The scheduler use EFP to ensure the QoS for each service, show as

below:

� The UL scheduler ensures the PELR and PDB as well as the service rate

for GBR services

� The UL scheduler uses a best effort policy for non-GBR services and

ensures only the minimum GBR specified by the UlMinGbr parameter

� If GBR and non-GBR services run simultaneously, GBR services take

precedence over non-GBR services

� eNodeB scheduler and UE scheduler are involved together on UL

scheduling, eNodeB scheduler decide the total resource for each UE

and UE scheduler decide the priority of each logic channel

scheduling.

Page39





Token Bucket Rate Control in eNB

Page40


Service Priority in UE Scheduler

� The differentiation between services with different QCIs is

achieved by setting the logical channel priority and

prioritized bit rate

Logical Channel Type PRB Configuration Priority

QCI 1 8 kbyte/s Not configurable

QCI 2 to QCI 4 Configurable Not configurable

QCI 5 8kbyte/s Not configurable

QCI 6 to QCI 9 Configurable Configurable

Page41





Pre-Allocation Scheduling

Pre-Allocation Non Pre-Allocation

Page42


Contents

1. Overview




Page43





VoIP Service Status

� Transient state: A newly set up service is unstable

� Talk spurt: User is in normal conversation

� Silent period: User pauses during the conversation. In this

state, a silence insertion descriptor (SID) frame is

transmitted every 160 ms.

Page44


Scheduling Scheme

� VoIP initial, transient and silent period: Adopt dynamic scheduling

� Talk spurt: Normally use semi-persistence scheduling except the following scenarios:

� High speed scenario

� UE has the other EPS bear more beside VoIP

� The cell bandwidth is 1.4 MHz

� UEs request emergency calls

Page45





Semi-Persistence Scheduling

� In semi-persistent scheduling mode, the VoIP service

quality can be better ensured because the transmitted DL

data has a priority that is second only to that of common

control information.

� MCS selection: It is the very similar as dynamic scheduling,

but the maximum MCS IMCS can only be 15, If the derived

IMCS is greater than 15, the eNodeB takes IMCS as 15.

Page46


Resource Limitation

� In order to avoid too much resource occupation by semi-

persistent scheduling, we can set a threshold to limit semi-

persistent service. If the total PRB used by semi- persistent

service is more than threshold in a TTI, then eNB stop the

scheduling for the other semi-persistent service and also it

stops the admission for this service

Page47





Reference: Parameter description (1/5)

� For detail, please refer to the notes.

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Thank youwww.huawei.com

microsoft powerpoint - oeo106040 lte eran6.0 scheduling feature issue 1

Documents

huawei technologies

scheduling featurecopyright

scheduling scheme period

real time service

real time gaming4 gbr

conversational voice2

conversational voice3

tti service application